A non-oriented electrical steel sheet is used as a material for an iron core in rotary devices such as motors and generators, and stationary devices such as small transformers, and plays an important role in determining energy efficiency in electric devices.
The representing characteristics of the electrical steel sheet may include iron loss and magnetic flux density. In general, it is preferable that the iron loss becomes smaller and the magnetic flux density becomes higher. This is because when a magnetic field is induced as the iron loss becomes small the energy being lost in the form of heat can be reduced, and as the magnetic flux density becomes high a larger magnetic field can be induced with the same amount of energy.
Accordingly, in order to comply with the growing demand for reducing energy usage, and environmentally-friendly products, it is necessary to develop a technology for manufacturing a non-oriented electrical steel sheet.
Representing methods of improving iron loss among the magnetic properties of the non-oriented electrical steel sheet may include a method of reducing the thickness of the steel sheet, and a method of adding elements such as Si and Al, which have relatively high resistivity.
However, there is a problem in that the thickness is generally determined based on the characteristics of the product being used, and the thinner the thickness the higher the production cost and the lower the productivity.
In reducing the iron loss by increasing electrical resistivity of a conventional material by adding alloy elements such as Si, Al, Mn, etc., which have relative high resistivity, the method may reduce the iron loss with the addition of the alloy elements but there is a discrepancy that the decrease in saturated magnetic flux density will eventually lead to a decrease in the magnetic flux density.
Further, when the amount of Si being added becomes 4% or higher, it deteriorates the processability and makes the process of cold rolling difficult, thereby reducing productivity. Furthermore, as the amount of Al, Mn, etc., being added increases, the rolling is deteriorated and the hardness increases thereby reducing productivity.
Meanwhile, C, S, N, Ti, etc., which are impurity elements essentially added to steel, bind to Mn, Cu, Ti, etc. and form fine inclusions with a size of about 0.05 μm, thereby preventing the growth of grains and magnetic domains, and as a result, magnetic properties of the steel are deteriorated.
It is difficult to maintain these impurities at an extremely low level using a conventional manufacturing process, and the inclusions themselves are also hard to control because they undergo re-dissolution and precipitation according to their respective manufacturing processes.
Therefore, a technology for manufacturing clean steel by increasing a texture {100}, which is useful for improving magnetic properties, via the addition of a small amount of an alloy element in order to improve the magnetic flux density while lowering iron loss, and by reducing a texture {111}, which is a harmful set texture or by extremely lowering the amount of impurities, has been used.
However, the technology has drawbacks in that it increases production cost and has difficulties in mass production. Therefore, there is a need for the development of an improved technology that improves magnetism while preventing the increase in production cost.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.